Preparation of organothiophosphorus halides



United States Patent Oflice 3,457,306 PREPARATION OF ORGANOTHIOPHOSPHORUS HALIDES Joseph W. Baker, Kirkwood, and Raymond E. Stenseth, St. Louis, Mo., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Dec. 22, 1965, Ser. No. 515,721 Int. Cl. C07f 9/42, 9/20 US. Cl. 260-543 11 Claims ABSTRACT OF THE DISCLOSURE Process for the preparation of organophosphonothioic dihalides [RP(S)X and diorganophosphinothioic halides [R P (S)X which comprises heating a compound of the formula (RS) PX at a temperature above about 200 C. in the presence of a halide catalyst wherein R is hydrocarbyl of not more than 18 carbon atoms and X is halogen.

This invention relates to an improved process for the preparation of compounds of phosphorus and more particularly to an improved process for the preparation of organophosphonothioic dihalides and diorganophosphinothioic halides.

Organophosphonothioic dihalides and diorganophosphinothioic halides have been prepared heretofore by the thermal rearrangement of organothiophosphorodihalidites, di(organothio)phosphorohalidites and mixtures thereof in the liquid or vapor phase at a temperature above about 200 C. This thermal rearrangement process, which is disclosed and claimed in copending application Ser. No. 515,765, can be represented by the following nonstoichiometric expressions A II II RSPX: RPXQ RgPX A i i (RSMPX RPX: RaPX A II II RSPX; (RShPX RPX; RQPX wherein R and X are as defined above. In accordance with the above represented reactions, the process of this invention results in the concomitant production of organophosphonothioic dihalides [RP(S)X and diorganophosphinothioic halides [R P(S)X]. In reaction (a) above the organophosphonothioic dihalides generally comprise a major amount of the product phosphorus compounds whereas in reaction (b) above the organophosphonothioic dihalides generally comprise a major amount of the product phosphorus compounds. Thus, in reaction above, the ratio of organophosphinothioic dihalide to diorganophosphinothioic halide in the product phosphorus compounds depends upon the ratio of the RSPX and (RS) PX reactants. In said process the yield is often uneconomical unless the liquid phase thermal rearrangement is carried out at high temperatures for long periods of time.

Accordingly, an object of this invention is to provide an improved liquid phase process for the preparation of organophosphonothioic dihalides, diorganophosphinothioic halides, and mixtures thereof. Other objects will be apparent from a consideration of the following disclosure.

The above and other objects of this invention are accomplished by carrying out the thermal rearrangement of organothiophosphorodihalidites, di(organothio)phosphorohalidites and mixtures thereof in the presence of a halide catalyst. The use of a halide catalyst in accord- 3,457,306 Patented July 22, 1969 pounds selected from the group consisting of (a) compounds of the formula (2n) S=P wherein R, which can be the same or different, is hydrocarbyl of notmore than 18 carbon atoms bonded to the phosphorus atom through a carbon-phosphorus bond, X is halogen (Cl, Br, F and I) and n is an integer from 0 to 1, and (b) mixtures thereof are prepared by the process which comprises heating a compound selected from the group consisting of (a) compounds of the formula (R 3) (2-n) P -X (l-l'n) wherein R is hydrocarbyl of not more than 18 carbon atoms and X and n are as defined above, and (b) mixtures thereof at a temperature above about 200 C. in the liquid phase in the presence of a halide catalyst se lected from the group consisting of (a) organic halides of the formula (R'iX wherein R is hydrocarbyl of not more than 18 carbon atoms selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl and aralkyl, X is halogen (Cl, Br, I and F) and m is an integer from 1 to 3, (b) inorganic halides of the formula MeX wherein Me is selected from the group consisting of metal and NH X is halogen (Cl, Br, I and F), v is the actual valence of Me and is an integer from 1 to 6 and (c) halogens selected from the group consisting of C1 Br and I Mixtures of the above halide catalysts also can be employed in the process of this invention.

Representative organic halide catalysts of the formula (R'-}X which can be used in this invention include by way of example alkyl halides such as methyl chloride, methyl iodide, methyl bromide, methyl fluoride, ethyl chloride,

ethyl iodide,

ethyl bromide,

ethyl fluoride, dichloroethane, n-propyl chloride, n-propyl bromide, isopropyl iodide, n-butyl bromide, sec-butyl iodide, tert-butyl bromide, 1,3,3-trichlorobutane, 1,3,3-tribromobutane, pentyl chloride, pentyl bromide,

the straight and branched chain nonyl, decyl, hexadecyl, undecyl, heptadecyl and dodecyl, octadecyl chloride, tridecyl, bromides, tetradecyl, fluorides and pentadecyl, iodides;

alkenyl halides such as S-chloro-n-butylene-l, 3-chloro-n-pentylene-1, 4-chloro-n-hexylene-2,

the varioushomologues and isomers of alkenyl halides having 2 to 18 carbon atoms; alkynyl halides suchas propargyl chloride, propargyl bromide, propargyl iodide and the various homologues and isomers of alkynyl halides having 3 to 18 carbon atoms; cycloalkyl halides such as chlorocyclopentane, bromocyclopentane, 2,4-dichlorocyclopentane, chlorocyclohexane, bromocyclohexane, 2,4-d1- chlorocyclohexane, 2,4,S-trichlorocyclohexane, chlorocyclheptane, 2,5-dichlorocycloheptane, 2,4,5-tribromocycloheptane and the like, and aralkyl halides such as benzyl chloride, benzyl bromide, chlorophenylethane, bromophenylethane, 2,4-dichlorophenylethane, 2,4,-trichlorophenylethane, 2,4,6-tribromophenylethane, di(2,4 dichlorophenyl)methane and the like. The preferred organic halide catalysts of the formula (R'lX are those wherein R is alkyl, alkenyl, alkynyl, cycloalkyl or aralkyl having not more than 8 carbon atoms, X is chloride and m is an integer from 1 to 3.

Representative metallic halide catalysts of the formula MeX which can be used in this invention include by way of example the halides of Na, K, Ti, Ba, Al, Sb, As, Be, Bi, Cd, Ce, Co, Cu, Ga, Au, In, Fe, La, Pb, Mn, Hg, Nb, Ni, Os, Re, Se, Ag, Ta, Tl, Sn, Zn, and the like.

Specific examples of suitable inorganic halide catalysts of the formula MeX include by way of example: AlBr A101 AlF DbBr SbCl SbI SbCl SbI SbI AsBr ASC13, Nbcis, NiBI'g, NlIz, OSFS, RcCl ASP-3, AsI BeBr BeCl BeF B612, BiBr BiCl BiBr Bil CdBr ReC1 SeF AgBr, AgF, AgI, TaCl CdCI CdF Cdl CeCl CoBr CoCl Col CuBr, CuBr CuCl, cuclz, TaBr3, TlCl SHBI'Z, Snclz, ZDBI'Z, ZnCl CUI, GaBr GaCl GaI AuBr, AuBr AuCl, AuCl A1113, lnBr InCl ZnI NaCl, NaI, NaBr, KCl, NH Cl, InI FeBr FeBr 'FeCl FeCl FeBr FeI LaBr LaCl L313, PbBfz, KBI', SnCl TiBr TlI4, NH4I, PbC12, Pbi MnBr MnCl MnI HgBr HgBrI, HgCl HgF Hgl NbBr ,'ReCl T aCl ZnCl KI, BaC1 NH Br.

The amount of catalyst employed is not critical. The

exact amount will vary somewhat depending upon the specific catalyst and the specific R group in the phosphorus compounds of the formula RSPX and (RS) PX to be rearranged. The catalyst is present in a catalytic amount, generally from about 0.0005 mol. to about 0.2 mol. per mol. of phosphorus compounds to be thermally rearranged. However, greater or lesser amounts can be employed. Preferably, the catalyst is present in an amount of at least about 0.005 mol. per mol. of phosphorus compounds to be thermally rearranged.

Representative R hydrocarbon radicals for the compounds of the above formulae prepared by the process of this invention include by way of example alkyl (1 to 18 carbon 'atoms) such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and the various homologues and isomers of alkyl having from 1 to 18 carbon atoms, cycloalkyl and alkyl substituted cycloalkyl (3 to 18 carbon atoms) such as cyclopentyl, cyclohexyl, monoand polymethylcyclohexyl, monoand polyethylcyclohexyl, cycloheptyl and the like, cycloalkenyl and alkyl substituted cycloalkenyl (3 to 18 carbon atoms) such as cyclopentenyl, cyclohexenyl, cycloheptenyl, monoand polyethylcyclohexenyl and the like, aryl (6 to 18 carbon atoms) such as phenyl, biphenyl, naphthyl, and the like, aralkyl (7 to 18 carbon atoms) 4 such as benzyl, phenylethyl, diphenylmethyl and the like, alkaryl (7 to 18 carbon atoms) such as tolyl, ethylphenyl, xy lyl, butylphenyl, tert-butylphenyl, trimethylphenyl, diethylphenyl, methylpropylethylphenyl and the like.

The thermal rearrangement of this invention can be carried out by heating organothiophosphorodihalidites, di- (organothio) phosphorohalidites or mixtures thereof in the liquid phase at temperatures from about 200 C. to about 350 C. Temperatures below about 200 C. can be used but reaction time is increased substantially at such lower temperatures. Preferably the reaction is carried out at temperatures above about 225 C. from the standpoint of optimum conversion in reasonable reaction periods. The reaction can be carried out at subatomspheric, atmospheric or superatmospheric pressures, the pressure not being critical. The exact reaction conditions, i.e., time, temperature and pressure, Will depend upon the specific compounds to be thermally rearranged. The thermal rearrangement can be carried out in the presence of an inert organic medium. Suitable organic media include for example Decalin, Tetralin, chlorinated biphenyl and the like.

The separation of the desired phosphorus compound from the product mixture is readily accomplished by conventional means well-known in the art, e.g., fractional distillation under reduced pressure, selective extraction, fractional distillation using a carrier gas, film distillation, elution or any suitable combination of these methods.

The phosphorus compounds prepared by the thermal rearrangement of this invention and numerous uses therefor are well-known in the art. These compounds are useful as fire retardants and rust inhibitors, and as chemical intermediates in the preparation of petroleum additives, agricultural chemicals, organophosphorus polymers and other products of commercial interest. For example, valuable lubricity additives for lubricating oils can be prepared by reacting phosphorus compounds prepared by the process of this invention with phenol at temperatures from about C. to about C. in the presence of an acid acceptor in accordance with the following equations wherein R and X are as defined above.

The following examples will illustrate the invention. Parts and percent are by weight unless otherwise indicated.

EXAMPLE 1 A reaction vessel equipped with stirrer, thermometer, Dry Ice condenser and inlet tube is charged with 549.4 parts of phosphorus trichloride. While maintaining the temperature at about 65 C. and stirring, 190.0 parts of methyl mercaptan are introduced into the vessel through the inlet tube below the surface of the liquid over a period of about six hours. After the addition of methyl mercaptan, the reaction mixture is stirred until the evolution of HCl is substantially complete. Nuclear magnetic resonance (NMR) spectrum analysis shows that the product mixture contains, based on the total mols of phosphorus compounds present, 59 mol percent of methylthiophosphorodichloridites and 20 mol percent of di(methylthio)- phosphorochloridites.

EXAMPLES 2 TO 13 The CH SPCl -(CH S) PCl mixture prepared in Example 1 above is divided into portions and each portion is admixed with a catalyst as given in Examples 2 to 13 except for control Example 2. The reaction mixtures of CH SPCl (CH S) PCl and catalyst are sealed in a reaction vessel and heated at 275 C. for eight hours. At the end of this period the vessrls are cooled to room temperature and the products removed. The thermally rearranged product mixtures are subjected to gas chromatographic analysis. Results and further details are given in Table 1 below.

TABLE I Product 2 Ex. Catalyst Amount 1 OH3P(S)C12 (CH3)2P(S)C None 43 9. 1 0. 025 66.7 7. 9 0. 05 51. 7 13.4 0. 05 65. 9. 3 0. 61. 1 9. 2 0. O5 49. 6 8. 9 0. 05 52. 5 10. 8 0. 05 60. 2 7. 3 0. 05 61. 0 5. 4 O. 05 49. 9 4. 7 O. 05 48. 4 9. 7 0. 05 47. 4 8. 2

1 Catalyst expressed as mol per mol of OH3SICl l(CHiS)zP Cl. Weight percent of total product mixture.

EXAMPLES 14 TO Various reaction mixtures containing compounds of the formula RSPX +(RS) PX are sealed in a reaction vessel and heated at 275 C. for eight hours in the presence of the catalysts listed in Table II below. At the end of this period the vessels are cooled to room temperature and the products removed. The thermally rearranged product material is subjected to NMR spectrum analysis. In all cases results comparable to those of Examples 3 to 13 above are obtained.

TABLE II Reaction mixture RSPX2+(RS)2PX Ex. R X Catalyst Amount 1 14. Ethyl Cl Ethylene dibromide 0.06 15 Propyl Cl NHiBr 0.001 6 Hexyl Br NHiCl 0.0005 I 1,3,5-triiodopentaue. 0. 002 Propargyl bromide 0.001 Allyl chloride 0. 005 l-bromo-3-iodocyclo 0. 006

hexane. 21. Cycloheptyl Cl 2,2-dichlorodecane 0.001 22. CyclohexyL Cl 3-ehloromethyln- 0. 007

pentylene-l.

2-chlorocyclo heptane 0. 2 Benzyl chloride. 0.006 Butyl bromide 0. 005

1 Mols of catalyst per mol of phosphorus compounds (RSPX2+ (RS)ZPX] to be rearranged.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Process for the preparation of phosphorus compounds selected from the group consisting of (a) compounds of the formula wherein R is hydrocarbyl of not more than 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, cycloalkenyl, aryl, aralkyl and alkaryl, X is se lected from the group consisting of Cl, Br, F and I and n is an integer from 0 t0 1, and (b) mixtures thereof which comprise heating a member selected from the group consisting of (a) compounds of the formula wherein R, X and n are as defined above and mixtures thereof at a temperature from about 200 C. to about 350 C. in the presence of a halide catalyst selected from the group consisting of (1) organic halides of the formula (R'iX wherein R is hydrocarbyl of not more than 18 carbon atoms selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl and aralkyl, X is halogen and m is an integer from 1 to 3, (2) inorganic halides of the formula MeX wherein Me is selected from the group consisting of Na, K, Ti, Ba, Al, Sb, As, Be, Bi, Cd, Ce, C0, Cu, Ga, Au, In, Fe, La, Pb, Mn, Hg, Nb, Ni, Os, Re, Se, Ag, Ta, Tl, Sn, Zn and NH X is as defined above and v is the valence of Me and is an integer from 1 to 6, and (3) halogens selected from the group consisting of C1 Brg and I2.

2. Process of claim 1 wherein R is alkyl.

3. Process of claim 1 wherein R is aryl.

4. Process of claim 2 wherein R is methyl.

5. Process of claim 3 wherein R is phenyl.

6. Process of claim 1 wherein the halide catalyst is an organic halide.

7. Process of claim 6 wherein the organic halide is methyl iodide.

8. Process of claim 1 wherein the halide catalyst is an inorganic halide.

9. Process of claim 1 wherein R is methyl and the halide catalyst is I 10. Process of claim 1 wherein R is methyl and the halide catalyst is CH I.

11. Process of claim 1 wherein R is methyl and the halide catalyst is ZnI References Cited UNITED STATES PATENTS 3,078,304 2/1963 Niebergall. 3,184,496 5/1965 Baranauckas et al. 260969 3,337,658 8/1967 Senkbeil et al 260960 OTHER REFERENCES Kosolapoif: Organop-hosphorus Compounds O) pp. 187, 193.

BERNARD HELFIN, Primary Examiner J. E. EVANS, Assistant Examiner US. Cl. X.R. 

